Eichhornia crassipes (water hyacinth, "Hoteiaoi")

Japanese name: ホテイアオイ （布袋葵）
Scientific name: Eichhornia crassipes

[Overview]
A floating aquatic perennial. In cold regions it is treated as an annual.
The leaves are obovate, 4–10 cm long and 4–10 cm wide, and the leaf stalks swell into float-like bladders.
A raceme is produced on an erect flower stalk.
The flowers are pale bluish purple, about 5 cm across; the corolla is 6-lobed, and the upper lobe has a yellow spot in the center surrounded by a somewhat deeper bluish purple.

[History]
It is said to have been brought back from America as an ornamental plant in the Meiji era, then escaped and became naturalized.

[Cultivation]
Propagate by division of the stolons.
It prefers a sunny location, and with sufficient warmth and light it multiplies very readily without any particular care.
It is enough simply to leave the plant floating on water.
In principle, no fertilizer is given, since it would make the plant grow huge or multiply explosively.
It has weak cold tolerance and dies back when exposed to frost.
Aphids may appear in summer.

[Notes]
The name compares the swollen leaf stalks to the belly of Hotei (a god of good fortune).
It is designated as an invasive alien species requiring caution.

View this page in Japanese (日本語)